\(\frac{13\pi}{6}\) is coterminal with which smaller positive angle?

Correct answer: \(\frac{\pi}{6}\)

Coterminal angles differ by an integral multiple of \(2\pi\). Since \(2\pi=\frac{12\pi}{6}\), \(\frac{13\pi}{6}-2\pi=\frac{13\pi}{6}-\frac{12\pi}{6}=\frac{\pi}{6}\). Hence, the smaller positive coterminal angle is \(\frac{\pi}{6}\). Although \(\frac{7\pi}{6}\) is positive, its difference from \(\frac{13\pi}{6}\) is \(\pi\), not a multiple of \(2\pi\). Exam tip: add or subtract \(2\pi\) to reduce an angle to \([0,2\pi)\).